Diversity and biogeography of coastal fishes of the East Cape Region of New Zealand C.D. Roberts and A.L. Stewart SCIENCE FOR CONSERVATION 260 Published by Science & Technical Publishing Department of Conservation PO Box 10–420 Wellington, New Zealand Cover: The dive boat Tu Taua during the survey at station E07, Boat Cove, Lottin Point, East Cape Region, on 1 May 1992. Photo: C.D. Roberts Science for Conservation is a scientific monograph series presenting research funded by New Zealand Department of Conservation (DOC). Manuscripts are internally and externally peer-reviewed; resulting publications are considered part of the formal international scientific literature. Individual copies are printed, and are also available from the departmental website in pdf form. Titles are listed in our catalogue on the website, refer www.doc.govt.nz under Publications, then Science and research. © Copyright January 2006, New Zealand Department of Conservation ISSN 1173–2946 ISBN 0–478–14049–5 This report was prepared for publication by Science & Technical Publishing; editing by Lynette Clelland and layout by Ian Mackenzie. Publication was approved by the Chief Scientist (Research, Development & Improvement Division), Department of Conservation, Wellington, New Zealand. In the interest of forest conservation, we support paperless electronic publishing. When printing, recycled paper is used wherever possible. CONTENTS Abstract 5 1. Introduction 6 2. Objectives 8 3. Methods 8 3.1 Survey methods 8 3.2 Fish collection and preservation 9 3.3 Fish identification 9 3.4 Survey areas, dates, effort, and vessels 10 3.4.1 All surveys 10 3.4.2 East Cape area 10 3.4.3 Bay of Plenty islands 13 3.5 Statistical analyses 15 4. Results 15 4.1 Stations surveyed and fishes recorded 15 4.1.1 Intertidal fish fauna 17 4.1.2 Estuarine fish fauna 17 4.2 Survey area accounts 18 4.2.1 East Coast 18 4.2.2 Coastal Bay of Plenty 19 4.2.3 Inshore Bay of Plenty islands 19 4.2.4 Offshore Bay of Plenty islands 20 4.3 Fish diversity 20 4.3.1 Cumulative species graphs 20 4.3.2 Species diversity with effort, depth, and area 22 4.3.3 Statistical differences between survey areas 25 4.3.4 Taxonomic diversity 26 4.4 Ichthyofaunal composition 27 4.4.1 Species numbers and composition 27 4.4.2 Dominant and abundant species 28 4.5 Fish distributions 28 4.5.1 Northern (n = 35 spp., 32.7%) 30 4.5.2 Widespread (n = 69 spp., 64.7%) 32 4.5.3 Southern (n = 2 spp., 1.9%) 33 4.5.4 Unknown (n = 1 sp., 0.9%) 33 4.5.5 Northern fishes with southern limit on East Coast 33 4.5.6 Biogeographic composition of reef fish faunas 34 5. Discussion 35 5.1 Fish diversity 35 5.1.1 East Cape Region 35 5.1.2 New records of fishes for the East Cape Region 37 5.1.3 White Island fishes 38 5.1.4 Coastal stations with high species diversity within the ECR 39 5.2 Biogeographic transition area 40 5.3 Future work 42 6. Acknowledgements 43 7. References 44 Appendix 1 Fish species identified from the coastal East Cape Region 47 Appendix 2 Fish species identified from Whale Island and Rurima Islets 52 Appendix 3 Fish species identified from White Island and Volkner Rocks 55 Diversity and biogeography of coastal fishes of the East Cape Region of New Zealand C.D. Roberts and A.L. Stewart Museum of New Zealand Te Papa Tongarewa, PO Box 467, Wellington, New Zealand ABSTRACT A fish survey was carried out along 300 km of coast in the East Cape Region (ECR), North Island, between Whakatane (Bay of Plenty) and Gisborne (Poverty Bay) New Zealand during 1992–1999. Sampling, using mainly rotenone ichthyocide and handspear, was carried out at 0–21 m depth by teams of 4–7 divers who spent c. 200 hrs underwater collecting fish specimens and recorded identification and habitat data. A total of 148 fish species (114 genera; 65 families) were recorded in inventory lists supported by voucher specimens. Of these, 107 shallow reef fish species were analysed to compare diversity and composition in four ECR subareas: East Coast, coastal Bay of Plenty (BOP), inshore BOP islands, and offshore BOP islands. No significant difference was found between the East Coast and the coastal BOP stations, and between the BOP inshore and offshore island stations; but there was a significant difference between all coastal stations (East Coast and BOP) and all island stations (inshore and offshore) using ANOVA and Tukey post hoc comparisons. Complementary results were obtained with Jaccard’s pair-wise comparison between composition of reef fish faunas, which indicated that offshore BOP islands were the least similar to coastal BOP and the East Coast (46% species shared respectively); and the East Coast and coastal BOP were the most similar (79% species shared). Most reef fishes in the ECR (78%) were widespread New Zealand species; and there was a moderate northern component (20%) and small southern component (2%). There were progressive changes in composition moving from west to east and from offshore to inshore, with a reciprocal decrease in northern species and increase in widespread species, and a small increase in southern species. Northern species reached their limit of distribution variously at White Island, coastal BOP, East Cape, and East Coast; southern species reached their limits at East Cape. All these results provide strong support for a wide biogeographic transition throughout the ECR, and refute a narrow biogeographic boundary. Keywords: coastal fishes, rotenone sampling, specimen collections, species diversity, rare species, new species, biogeography, East Cape, New Zealand © January 2006, Department of Conservation. This paper may be cited as: Roberts, C.D.; Stewart, A.L. 2006: Diversity and biogeography of coastal fishes of the East Cape Region of New Zealand. Science for Conservation 260. 57 p. Science for Conservation 260 5 1. Introduction Research on the marine biota of New Zealand carried out over the last 50 years has shown the East Cape Region (ECR), from Whakatane to Gisborne (Fig. 1), to be an important biogeographic feature influencing the distribution, composition, and diversity of intertidal, coastal and shelf communities, including algae (Moore 1949, 1961), molluscs (Powell 1961; Dell 1962), echinoderms (Pawson 1961, 1965; Baker 1968) and fishes (Moreland 1959). Early regional biogeographic work in New Zealand centred on the description of marine provinces (e.g. Powell 1961; Knox 1963), with almost complete agreement that East Cape defined the boundary between the Aupourian (Auckland or Northern) Province and the Cookian Province to the south, a division still in use today (Morton 2004: 186). Subsequent biogeographic research (e.g. Dell 1962; Pawson 1965) focussed more on the description and analyses of distribution patterns of species and areas of endemism around New Zealand, but nevertheless continued to show East Cape to be a major biogeographic feature. The nature of this feature however has varied substantially between studies, ranging from a well-defined barrier (e.g. Pawson 1961: 11, 1965: 248), poorly defined boundary (e.g. Dell 1962: 48; Knox 1963: 396), well-defined boundary (e.g. Moreland 1959: 30; Baker 1968: 6), to a methodological boundary line for subdivision of the coast in biogeographic studies of the New Zealand region (e.g. King et al. 1985: fig. 1; Paulin & Roberts 1993: fig. 88; Francis 1996: 37). For some groups, such as algae (Moore 1961; Adams 1994), echinoderms (Pawson 1965) and fishes (Waugh 1973: fig. 11.1; Paulin & Roberts 1993; Francis 1996), there is evidence that northern species—some widely Australasian or Indo-Pacific and some endemic to a relatively small area of New Zealand—reach the southern limit of their distribution at or near East Cape. Conversely, southern and central New Zealand species extend north to East Cape. However, this generalisation may be overly simplistic (Morton & Miller 1968: 336) and there have not been adequate surveys of key marine groups to assess the species present and their biogeographic relationships. Hypotheses of the ECR supporting marine habitats with boundary or transitional marine biota have not, therefore, been adequately tested. Walls (1995) identified an information gap for the ‘transition zone between East Cape and Hawkes Bay’, and recommended that research should target the area. The fish team from the Museum of New Zealand Te Papa Tongarewa (Te Papa) has been carrying out a long-term programme to survey and sample fishes in New Zealand coastal waters. Opportunistic fieldwork to collect and preserve fishes from the ECR began in the 1980s. Comprehensive fieldwork involving teams of divers, began in the early 1990s as part of a joint Museum of New Zealand/Department of Conservation (DOC) programme to survey, collect and inventory coastal marine reef fishes. Since then, fieldwork has been carried out for from one to two weeks during summer in 1992, 1993, 1998, and 1999, in the area between Gisborne and the eastern Bay of Plenty, including sites at nearshore and offshore islands. 6 Roberts & Stewart—Diversity of coastal fishes, East Cape Figure 1. Locations of coastal stations sampled in the East Cape Region during the 1992, 1993, and 1999 fish surveys. For the coastal fish fauna, the survey sought to answer several questions about diversity and distribution of reef fishes in the ECR. The answers to these questions will assist the Department of Conservation assess the value and location of sites for marine reserves in the region, and provide essential baseline data that can be used in monitoring programmes. Currently there is one marine reserve in the ECR: Te Tapuwae o Rongokako, 16 km north of Gisborne. Other marine protected area proposals are being investigated.